ABSTRACT Objective To improve the accuracy of ultrasound diagnosis of the disease by analyzing and summarizing the characteristics of Morel-Lavallée lesion (MLL). Methods The clinical and ultrasound data of 22 cases of Morel-Lavallée lesion was retrospectively analyzed，which were clinically confirmed from March 2018 to May 2021. The contents of color Doppler ultrasonography are the lesion’s location

shape

size

internal echo characteristics

capsule

septation

and blood flow signal

etc. Results All of 22 cases had a clear history of trauma

all of which were gradually enlarged masses in the subcutaneous soft tissue of the wound. 22 lesions were found and located between the subcutaneous fat and deep fascia

and the shape was crescent-shaped (n=14)

fusiform (n=4)

or irregular (n=4)

with intact capsule (n=18) or incomplete (n=4). Some membranous hypoechoic echo could be seen in 6 cases. The smallest size of the lesion was 2.5 cm×1.1 cm×0.4 cm

and the largest one was 10.5 cm×5.6 cm×2.6 cm. In this group

68.2% of the lesions were weak echo (15/22)

among them

fat nodules were seen in 5 cases and membranous hypoechoic structures were seen in 6 cases. And 31.8% were homogeneous hypoechoic (7/22). And 7 cases were accompanied by muscle edema around the lesions

all accompanied by swelling of the peripheral subcutaneous fat layer and enhanced echo. Conclusions Ultrasound manifestations of MLL have certain characteristics

most of which are weak echo or heterogeneous hypoechoic masses between subcutaneous fat and deep fascia

often with intact capsules. Sometimes there are some membranes hypoechoic contents and fatty nodules. Ultrasound-guided puncture is beneficial for the diagnosis and treatment of MLL.